PRE-SULFIDING & ON-LINE SULFIDING of VULCAN Series CoMo and NiMo Catalyst in Synthesis Gas Applications

1. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
GBH Enterprises, Ltd.
PRE-SULFIDING & ON-LINE SULFIDING of
VULCAN Series CoMo and NiMo Catalyst in
Synthesis Gas Applications
Process Information Disclaimer
Information contained in this publication or as otherwise supplied to Users is
believed to be accurate and correct at time of going to press, and is given in
good faith, but it is for the User to satisfy itself of the suitability of the Product for
its own particular purpose. GBHE gives no warranty as to the fitness of the
Product for any particular purpose and any implied warranty or condition
(statutory or otherwise) is excluded except to the extent that exclusion is
prevented by law. GBHE accepts no liability for loss, damage or personnel injury
caused or resulting from reliance on this information. Freedom under Patent,
Copyright and Designs cannot be assumed.

2. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
PRE-SULFIDING & ON-LINE SULFIDING PROCEDURES IN SYNGAS
APPLICATIONS
VULCAN Series VHT-S101/S103
GENERAL
The purpose of the CoMo or NiMo HDS catalyst is to convert organic sulfur
compounds such as mercaptans, sulfides and thiophenes to H2S, which can then
be absorbed by zinc oxide. The organic sulfur compounds are converted to H2S
by reaction with hydrogen in the feed. Simple compounds also crack thermally at
temperatures in the range 150-400°C forming H2S and (in the absence of
hydrogen) olefins.
The catalysts do not normally require being sulfided before operation. They have
sufficient initial activity and become adequately sulfided by reaction with the
sulfur compounds in the process stream during normal operation.
Pre-sulfiding and on-line sulfiding should be considered in three situations,
a) The initial feed contains < 2 ppmv total sulfur, especially where there is a
high hydrogen content (e.g.: refinery off gas feed) and S << 1 ppmv.
b) If the HDS catalyst is required to operate downstream of a zinc oxide bed,
such as in a system with 2 vessels each containing HDS and zinc oxide
catalysts. In this case, the second HDS catalyst would operate for a long
period in a sulfur free gas.
c) The initial feed is a high sulfur naphtha where there is > 20 ppmw S as
thiophenic sulfur compounds.
During normal operation in cases (a) and (b) it is advised to provide continuous
or periodic sulfur dosing.
This document deals with the pre-sulfiding and on-line sulfiding procedures in
turn;

3. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
PRE-SULFIDING PROCEDURE
Pre-sulfiding should achieve a sulfur loading of 1 -2 wt% on the catalyst. It is
carried out on fresh catalyst delivered to site in the oxide form.
• To bring the VULCAN VHT-S101/S103 catalyst to the sulfided and active
state, a quantity of at least 1 wt% of sulfur per weight of catalyst has to be
brought on to the catalyst before feed is introduced into the front-end of
the hydrodesulfurization (HDS) reactor.
• Dimethyl Disulfide (DMDS) contains approximately 1kg of sulfur per 1.5
liters of liquid
• DMDS will be injected into a nitrogen flow via small pump and the
resulting gas mixture will be injected into the Hydrodesulfurization (HDS)
reactor at the top of this reactor.
• DMDS injection will be continued till a sufficient quantity of DMDS has
been injected (See above).
• DMDS injection can be started when the inlet, outlet and bed
temperatures of the HDS reactor bed are all indicating at least 230°C.
Procedure:
1. The HDS reactor bed is heated up to a temperature of 230°C with nitrogen
circulation, with steam flowing through the reformer. The gas space
velocity used should be as close to full feed rate as possible, to ensure
good gas distribution. There will be a minimum flowrate which needs to be
used to ensure that adequate gas distribution is attained, for an adiabatic
catalyst bed this is typically around 300 hr -1
.
2. Make sure that the HDS reactor bed is heated up equally by checking its
inlet, outlet and bed temperatures.
3. In situ pre-sulfiding will be achieved by a nitrogen atmosphere and dosing
of DMDS.
4. As soon as the temperatures, as indicated under point 2, are at least
230°C and are stable, the in situ pre-sulfiding atmosphere can be initiated.

4. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
5. The nitrogen flow fed through the front end of the unit can be vented
to flare.
6. Make sure that after the introduction of nitrogen to the HDS reactor the
temperatures, as indicated under step 2, are still at least 230°C and are
stable before the DMDS dosing is allowed to start.
7. DMDS dosing can be started with a rate of 10 l/hr. For HDS catalyst in situ
pre-sulfiding it is usual to use around 1% (v/v) of the sulfur compound.
When DMDS injection is started, the actual DMDS injection flow should be
noted.
8. As soon as DMDS dosing has initiated the HDS reactor outlet gas should
be monitored continuously (every 5 minutes for the first half hour) for the
presence of total sulfur (for instance with Dragger tubes), to check if in situ
pre-sulfiding has commenced or not.
In situ pre-sulfiding has commenced when the HDS reactor outlet gas,
directly downstream of the HDS catalyst and upstream of the ZnO H2S
removal absorbent, shows no sulfur present.
9. If the HDS reactor outlet gas shows the presence of (total) sulfur in bulk, in
situ pre-sulfiding has not commenced, and the dosing of DMDS should be
immediately stopped.
10. When DMDS dosing has been stopped warm up the HDS reactor further
by 20°C to a temperature of 250°C.
11. As soon as the temperatures as indicated under point 2 are at least 250°C
and are stable, DMDS dosing at a dosing rate of 10 l/hr is allowed to start
again in the exact order as indicated above.
12. Repeat steps 9, 10 and 11. Every time the in situ pre-sulfiding has not
commenced raise the temperatures as indicated under step 2 by 20°C
before trying again.
A maximum temperature limit of 300 C is advisable until the in situ pre-
sulfiding procedure is complete.

5. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
13. After the first half hour of continuous measurement (as above) if the
HDS reactor outlet gas does not show a total sulfur presence, monitoring
can be reduced to every half hour, with the DMDS concentration in the
nitrogen being kept constant throughout.
During the in situ pre-sulfiding procedure there should be no total sulfur in
the exit from the HDS catalyst and upstream of the ZnO (VULCAN VSG-
S201) absorbent.
14. DMDS injection should be continued until the required amount of DMDS
required has been injected (See above). As soon as at least this amount
of DMDS has been injected DMDS injection can be stopped.
15. The HDS reactor will be warmed up further to temperatures ready for
introducing hydrocarbon feed into the unit.
The feed as should be introduced as per normal recommended start up/
operating procedures.

6. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
ON-LINE SULFIDING PROCEDURE
In order to maintain the catalyst in a sulfided state 2-3 ppmv S is required under
typical conditions. Should this level not be present on-line dosing is
recommended. This can either be via continuous injection of a sulfur source
(such as DMDS) at a level of 2-3 ppmv, or should be conducted every 8 - 10
weeks to deliver preferably 1 wt% S onto the HDS catalysts. This figure may be
less due to existing sulfur already on the catalyst from normal operation.
1. Ensure that the HDS reactor temperatures are at least 230°C and are
stable before the DMDS dosing is allowed to start.
2. DMDS dosing can be started with a rate of 10 l/hr. For HDS catalyst
periodic on-line sulfiding it is usual to use around 1% (v/v) of the sulfur
compound. Should the dosing be continuous a lower level may be
required.
When DMDS injection is started, the actual DMDS injection flow should be
noted.
3. As soon as DMDS dosing has initiated the HDS reactor outlet gas should
be monitored continuously (every 5 minutes for the first half hour) for the
presence of total sulfur (for instance with Dragger tubes), to check if on-
line sulfiding has commenced or not.
On-line sulfiding has commenced when the HDS reactor outlet gas,
directly downstream of the HDS catalyst and upstream of the ZnO H2S
removal absorbent, shows no sulfur present.
4. Should the outlet sulfur be equal to inlet sulfur, and the reactor is at
normal operating temperature, the catalyst is in the sulfided state. In this
case the dosing period (nominally 8-10 weeks) should be reviewed.
5. If the HDS reactor outlet gas shows the presence of (total) sulfur in bulk,
and the reactor is not at normal operating temperature, on-line sulfiding
has not commenced, and the dosing of DMDS should be immediately
stopped.
6. If DMDS dosing has to be stopped warm up the HDS reactor further to
normal operating temperature.

7. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
7. As soon as the temperature has reached the normal operating level
and is stable, DMDS dosing at a dosing rate of 10 l/hr is allowed to start
again.
8. After the first half hour of continuous measurement (as above) if the HDS
reactor outlet gas does not show a total sulfur presence, monitoring can
be reduced to every half hour, with the DMDS concentration in the
nitrogen being kept constant throughout.
During the on-line sulfiding procedure there should be no total sulfur in the
exit from the HDS catalyst and upstream of the ZnO absorbent.
9. DMDS injection should be continued until the required amount of DMDS
required has been injected (See above). As soon as this amount of DMDS
has been injected DMDS injection can be stopped.
10. The normal feedstock should be re-introduced as per normal
recommended start up/ operating procedures.
Note:
VULCAN Series Hydrogenation Catalyst in Hydrodesulfurization (HDS)
VHT-S101 Co, Mo, γ-Al2O3
VHT-S103 Ni, Co, Mo, γ-Al2O3
Other VULCAN Series HDS catalyst
VHT-S102 Fe, Mo, γ-Al2O3
VHT-N103 Ni, WO3, Mo, γ-Al2O3

8. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com